Grinding disk



April 1942- A. H. GRAENSER 2,279,673

I GRINDING DISK Filed May 25, 1940 I: -lllllllllllllllllllle ATTORNEY.

Patented Apr. 14, 1942 UNITED STATES PATENT ,OFFICE GRINDING DISK Alfred B. Graenser, Detroit, Mich., assignor of one-half to Delmar E. Meyer, Detroit, Mich.

Application May 25, 1940,.Serial No. 337,141

2 Claims.

This invention relates to grinding and polish ing disks and has for its primary object to provide a disk for use in conjunction with portable driving .apparatus, wherein the disk support is rotated by means of flexible shafting connected to a stationary motor or wherein the motor is also portable. The disk may thus be advantageously used for finishing rough metal surfaces during the manufacture of new automobile bodies and fenders as well as in the repair of damaged automobile bodies and fenders.

More specifically, the main object of the invention is to provide a disk of the type above referred to which may be reconditioned repeatedly. In this respect the invention provides for the attachment of the abrading material to its supporting member by the use of a water soluble cement so that in reconditioning the disk all that is necessary is to soak the disk in water, whereupon the cement will be dissolved and removed along with the abrasive material, thereby permitting application of a new coating of cement and abrasive.

Another object is to provide a disk assembly comprising a head, adapted to be rotatably dr ven, a cushion member carried by the head,

and a. metal disk overlying and backed by the.

cushion, The metal disk has abrading material" applied thereto as above mentioned, and is highly flexible. For example the disk is formed of steel of say ten thousandths of an inch thick, so that it may readily deflect in the presence of extrinsic forces.

The abrasive material is in some cases applied directly to the metal disk, while in other cases it is contemplated that the abrasive material will be applied to a fabric element by means of a water soluble cement, and that the fabric will, previously or subsequently, be attached to the disk by a waterproof or watersoluble cement.

The latter arrangement has an advantage from the standpoint of cheaper replacement in that the grinding surface may be replaced without re- I The fabric ele-- Fig. 3 is a section illustrating an alternative feature of construction, and

Fig. 4 is a section illustrating another mode of applying the abrading material.

More specifically, l designates a head adapted to be driven byflexible shafting connected to a stationary motor, or by a portable motor. These alternative operating means are now in common use in the automotive industry and are cited here by way of example, rather than by way of limitation. The disk hereinafter described, although ideally suited for this use, may, of course, be used under various other circumstances.

The head I has a comparatively large diameter radially extending flange 2 upon the outer face of which is secured a cushion 3, formed of rubber or equivalent material. This cushion is of fairly soft rubber and may be secured to the flange by an adhesive or by vulcanization. On the exposed face of the rubber cushion is a metal disk 4 having its center portion countersunk at 5 for the reception of the head of a screw 6 which secures the disc 4 on the rubber cushion and to the head I. The rubber cushion '3 is countersunk to receive the countersunk portion of the metal disk 4.

The metal disk 4 is made of very thin sheet steel of say ten thousandths of an inch thick, and is, therefore, highly flexible.

A circular piece I of fabric, preferably canvas,

is covered with a coating of water solvent cement, indicated by the heavy black line 8, and abrading material 9 is applied to the cement by sprinkling or rolling it thereon. The preferred adhesive is sodium silicate with 5 to 15% clay (bentonite for example) added thereto, the proportions depending upon the thickness of the abrading particles, In the case of larger abrading particles the amount of clay is increased, to

provide more body in the cement. The fabric I is secured .to the disk 4 by a waterproof or, preferably by a water soluble cement indicatedby the heavy black line I0.

When replacement of the abrasive surface becomes necessary the screw 6 is removed, thereby enabling removal of the disk 4. The disk 4 is soaked in water to dissolve the adhesive layers 8 and I0, thus leaving the disk 4 free for the application of a new abrasive covered fabric, and leaving the fabric free forthe application of another coating of abrasive material. 7

In Fig. 3, the construction is identical to that above described except that the disk 4a, which corresponds to the disk 4 above, is formed with a peripheral flange II for the purpose of stiffening the peripheral portion thereof. The ,reinforcement still permits flexing of the disk, but maintains the disk in flat surface contact with the rubber cushion 3a in the presence of securing means at only the center of the disk. In other words, the disk 4a is very thin and flexible, and

the reinforcing means acts to hold it in a perfectly flat condition.

In Fig. 4 the construction is similar to that above described and shown in Fig. 2. In this case the abrading material lb is secured directly to the disk 4b by a layer 8b of water soluble cement.

Although specific embodiments of the invention 4 head, said disk having a' cot -1tersunk portion for the reception of the head on the stud, said disk being normally flat and having a peripheral flange reinforcing the peripheral portion thereof against distortion from its normally flat condition, and abrasive particles secured to said disk by cement capable of being dissolved in water after it has become set.

2. A grinding disk assembly comprising a head, a rubber cushion, secured to a face of said head, a highly flexible thin metal disk overlying said cushion, means for securing the disk to the head with the cushion interposed therebetween, said means comprising a headed stud engaging said head, said disk having a countersunk portion for the reception of the head on the stud, said disk being normally fiat and having a peripheral flange reinforcing the peripheral portion thereof against distortion from its normally fiat condi tion, a layer of fabric secured to said disk by cement, and abrading particles secured to said fabric by a cement capable of being dissolved in water after it has become set.

ALFRED H. GRAENSER. 

